Question

Best way to teach addition with regrouping?

Answer 1

Agree, it is a good way, but it depends on the person learning. Not everyone makes enough effort to benefit from it.
If what you mean by regrouping is, adding (5,8,3,2,7)
would be equivalent to (mentally) adding (8,2, 3,7, 5) which gives obviously 25.
It would be a good method for someone who can add already, but would like to improve the addition skills, mentally or otherwise.
The same technique can be used to add bigger numbers too,
sum(26, 37, 92, 12, 45)=sum(26,92,12, 37,45)=sum(130,82)=212